Expandable vaporized pattern material for lost foam casting and preparation method thereof

Abstract

The invention provides an expandable vaporized pattern material for lost foam casting and a preparation method of the expandable vaporized pattern material, and belongs to the technical field of expandable vaporized pattern materials. The expandable gasified mold material provided by the invention is obtained by mixing and granulating the following raw materials: 10-40 parts of polystyrene, 30-60 parts of polymethyl methacrylate, 20-30 parts of polyether acrylate, 1-5 parts of SBS, 1-3 parts of a cross-linking agent and 5-20 parts of a foaming agent. The polyether acrylate is added, and a C-O ether bond of the polyether acrylate has relatively low fracture energy, so that the degradation temperature of the expandable vaporized pattern material can be effectively reduced, the expandable vaporized pattern material can be decomposed into energy required by small molecules more easily, and the residual carbon amount and the generation amount of cracking gas are reduced; the expandable vaporized model material provided by the invention does not need to be prepared by a suspension, and the problems of much wastewater, low strength and the like when the expandable vaporized model material is prepared by the suspension can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of expandable gasification mold materials, in particular to an expandable gasification mold material for lost foam casting and a preparation method thereof. Background Art

[0002] Gasification mold casting, also known as full mold casting or lost foam casting, is a foam mold with a closed-cell structure similar to that of a casting made of expandable bead material. The foam mold is processed and buried in filler sand, and the filler sand is compacted to have a certain molding strength. Then the mold is poured with molten metal liquid, and the foam mold is cracked and gasified when it contacts the high-temperature metal liquid, and the gas escapes into the air. The metal liquid fills the cavity, and the metal liquid is cooled to obtain a casting in the shape of the model. The thermal decomposition of the gasification mold in the presence of high-temperature metal liquid is a complex physical-chemical process, which will affect the heat transfer, mass transfer and momentum transfer in the liquid metal molding process. For example, the thermal decomposition process will affect the metal liquid filling process; the casting will produce certain casting defects related to the thermal decomposition products; the large amount of black smoke produced by the thermal decomposition of the gasification mold material will worsen the casting conditions and environmental hazards. Therefore, the thermal decomposition properties of the expandable gasification mold material in the presence of high-temperature metal liquid have a significant impact on the properties of the casting.

[0003] At present, the gasification mold materials that have been applied to lost foam casting include expandable polystyrene (EPS), expandable polymethyl methacrylate (EPMMA) and styrene-methyl methacrylate copolymer (STMMA). However, the above materials all have surface defects such as carbon black and slag inclusions caused by residual carbon in the solid product of high-temperature pyrolysis to varying degrees, so that the final castings of qualified quality cannot be obtained. In addition, the conventional preparation method of the above materials is aqueous suspension polymerization. On the one hand, the polymer beads obtained by this method have a small particle size and a low molecular weight, resulting in a high density of the mold material and a low compression strength of the mold; on the other hand, this preparation method requires the use of a large amount of water, and the amount of industrial wastewater is large.

[0004] Therefore, there is an urgent need to provide an expandable gasification mold material for lost foam casting which has low carbon content, high compressive strength, generates less cracking gas and can be prepared by a simple method. Summary of the invention

[0005] The object of the present invention is to provide an expandable gasification mold material for lost foam casting which has low carbon content, high compression strength, generates less cracking gas and can be prepared by a simple method and a preparation method thereof.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The invention provides an expandable gasification mold material for lost foam casting, which is obtained by mixing and granulating raw materials comprising the following components in parts by weight: 10 to 40 parts of polystyrene, 30 to 60 parts of polymethyl methacrylate, 20 to 30 parts of polyether acrylate, 1 to 5 parts of SBS, 1 to 3 parts of a crosslinking agent and 5 to 20 parts of a foaming agent.

[0008] Preferably, the preparation method of the polyether acrylate comprises: mixing polyether polyol and (meth)acrylate, and performing an ester exchange reaction to obtain the polyether acrylate.

[0009] Preferably, the temperature of the transesterification reaction is 100-120°C.

[0010] Preferably, the transesterification reaction time is 3 to 6 hours.

[0011] Preferably, the crosslinking agent comprises a peroxide crosslinking agent and / or an ultraviolet light crosslinking agent.

[0012] Preferably, the peroxide cross-linking agent is tert-butyl peroxide.

[0013] Preferably, the UV crosslinking agent includes one or more of triallyl isocyanurate, trimethylolpropane trimethacrylate and triallyl cyanurate.

[0014] Preferably, the blowing agent comprises CO2 or liquid nitrogen.

[0015] The present invention also provides a method for preparing the expandable gasification mold material for lost foam casting described in the above technical solution, comprising the following steps:

[0016] (1) mixing and melting polystyrene, polymethyl methacrylate, polyether acrylate, SBS and a crosslinking agent to obtain a polymer melt;

[0017] (2) mixing the polymer melt obtained in step (1) with a foaming agent and granulating the mixture to obtain polymer particles;

[0018] (3) Pre-foaming the polymer particles obtained in step (2) to obtain an expandable gasifiable mold material for lost foam casting; the pre-foaming atmosphere is water vapor with an oxygen volume content of not less than 21%.

[0019] Preferably, the temperature of the mixed melting in step (1) is 150-200°C.

[0020] The present invention provides an expandable gasification mold material for lost foam casting, which is obtained by mixing and granulating the raw materials including the following components by weight: 10-40 parts of polystyrene, 30-60 parts of polymethyl methacrylate, 20-30 parts of polyether acrylate, 1-5 parts of SBS, 1-3 parts of a crosslinking agent and 5-20 parts of a foaming agent. The present invention uses polystyrene and polymethyl methacrylate as the main components of the expandable gasification mold material, and adds polyether acrylate at the same time. The CO ether bond of the polyether acrylate has a lower fracture energy, which can effectively reduce the degradation temperature of the expandable gasification mold material, making it easier to decompose into the energy required for small molecules, and reducing the residual carbon amount and the amount of cracking gas generated; the expandable gasification mold material provided by the present invention does not require suspension preparation, and can solve the problems of large amount of wastewater and low strength when the expandable gasification mold material is prepared by suspension. The results of the embodiment show that the expandable gasification mold material provided by the present invention has the advantages of low carbon content, high compression strength and less cracking gas generation, and can be used for lost foam casting. DETAILED DESCRIPTION

[0021] The invention provides an expandable gasification mold material for lost foam casting, which is obtained by mixing and granulating raw materials comprising the following components in parts by weight: 10 to 40 parts of polystyrene, 30 to 60 parts of polymethyl methacrylate, 20 to 30 parts of polyether acrylate, 1 to 5 parts of SBS, 1 to 3 parts of a crosslinking agent and 5 to 20 parts of a foaming agent.

[0022] In the present invention, unless otherwise specified, the raw materials used in the present invention are all commercially available products well known in the art.

[0023] The raw materials for preparing the expandable gasification mold material for lost foam casting of the present invention include 10 to 40 parts of polystyrene, preferably 20 to 30 parts by weight. In an embodiment of the present invention, the grade of the polystyrene may be GPPS1050, GP5500 or 168M. The polystyrene used in the present invention has good strength, which is more conducive to improving the strength of the expandable gasification mold material.

[0024] Based on 10 to 40 parts by weight of polystyrene, the raw materials for preparing the expandable gasification mold material for lost foam casting of the present invention include 30 to 60 parts by weight of polymethyl methacrylate, preferably 35 to 55 parts by weight. In the embodiments of the present invention, the weight of the polymethyl methacrylate can be 35 parts, 40 parts, 45 parts, 50 parts or 60 parts. In the embodiments of the present invention, the source of the polymethyl methacrylate can be Shanghai MacLean Biochemical Technology Co., Ltd. In the present invention, the polymethyl methacrylate can make the expandable gasification mold material have good strength.

[0025] Based on 10 to 40 parts by weight of polystyrene, the raw material for preparing the expandable gasification mold material for lost foam casting of the present invention includes 20 to 30 parts by weight of polyether acrylate, preferably 25 to 30 parts by weight. In the present invention, the CO ether bond of the polyether acrylate has a lower fracture energy, which can effectively reduce the degradation temperature of the expandable gasification mold material, making it easier to decompose into the energy required for small molecules, and reducing the amount of residual carbon and the amount of cracking gas generated.

[0026] In the present invention, the method for preparing the polyether acrylate preferably comprises: mixing polyether polyol and (meth)acrylate, and performing an ester exchange reaction to obtain the polyether acrylate.

[0027] In the present invention, the functionality of the polyether polyol is preferably 3 to 10, more preferably 4 to 6; the relative molecular weight of the polyether polyol is preferably 500 to 5000, more preferably 1000 to 3000. In an embodiment of the present invention, the grade of the polyether polyol may be PPG-1000, PPG-2000 or PPG-4000.

[0028] In the present invention, the mass ratio of the polyether polyol to the (meth)acrylate is preferably (1-4): (2-3), and more preferably (3-4): (2-3). The present invention controls the mass ratio of the two within the above range, which is more conducive to the full reaction of the two.

[0029] The present invention has no particular limitation on the method for mixing the polyether polyol and the (meth)acrylate, as long as the two can be mixed evenly.

[0030] In the present invention, the temperature of the transesterification reaction is preferably 100-120°C, more preferably 110-120°C; the time of the transesterification reaction is preferably 3-6 hours, more preferably 4-5 hours. The present invention is more conducive to promoting the full reaction of polyether polyol and (meth)acrylate at the above temperature and time.

[0031] The raw material for preparing the expandable gasification mold material for lost foam casting of the present invention includes 1 to 5 parts by weight of SBS, preferably 2 to 4 parts by weight, based on 10 to 40 parts by weight of polystyrene. In the present invention, the melt index of the SBS is preferably 5 to 20 g / 10 min, more preferably 10 to 15 g / 10 min. The present invention uses SBS as a phase solubilizer to promote the compatibility of various components.

[0032] Based on 10 to 40 parts by weight of polystyrene, the raw materials for preparing the expandable gasification mold material for lost foam casting of the present invention include 1 to 3 parts by weight of a crosslinking agent, preferably 2 to 3 parts by weight. In the present invention, the crosslinking agent can generate free radicals on the molecular chain segments of polystyrene, initiating polymethyl methacrylate and polyether acrylate to form a graft copolymer thereon, so as to improve the compatibility of each component.

[0033] In the present invention, the crosslinking agent preferably includes a peroxide crosslinking agent and / or an ultraviolet crosslinking agent. In the present invention, when the crosslinking agent includes a peroxide crosslinking agent and an ultraviolet crosslinking agent, the mass ratio of the peroxide crosslinking agent to the ultraviolet crosslinking agent may be 1:1.

[0034] In the present invention, the peroxide crosslinking agent is preferably a tert-butyl peroxide peroxide. In an embodiment of the present invention, the model of the tert-butyl peroxide peroxide can be DYBP, bis(2-5-pyrrolidone) or DTBP. The present invention can cause the components to undergo peroxide thermal crosslinking by adding a peroxide crosslinking agent.

[0035] In the present invention, the ultraviolet crosslinking agent preferably includes one or more of triallyl isocyanurate, trimethylolpropane trimethacrylate and triallyl cyanurate. In an embodiment of the present invention, the model of the ultraviolet crosslinking agent can be TAIC, TMPTMA or TAC. The present invention can make each component undergo ultraviolet crosslinking by adding an ultraviolet crosslinking agent.

[0036] The raw material for preparing the expandable gasification mold material for lost foam casting of the present invention includes 5 to 20 parts by weight of a foaming agent, preferably 5 to 10 parts by weight, based on 10 to 40 parts by weight of polystyrene. In the present invention, the foaming agent can promote the foaming of the polymer. In the present invention, the foaming agent preferably includes CO2 or liquid nitrogen.

[0037] The present invention also provides a method for preparing the expandable gasification mold material for lost foam casting described in the above technical solution, comprising the following steps:

[0038] (1) mixing and melting polystyrene, polymethyl methacrylate, polyether acrylate, SBS and a crosslinking agent to obtain a polymer melt;

[0039] (2) mixing the polymer melt obtained in step (1) with a foaming agent and granulating the mixture to obtain polymer particles;

[0040] (3) Pre-foaming the polymer particles obtained in step (2) to obtain an expandable gasifiable mold material for lost foam casting; the pre-foaming atmosphere is water vapor with an oxygen volume content of not less than 21%.

[0041] The invention mixes and melts polystyrene, polymethyl methacrylate, polyether acrylate, SBS and a crosslinking agent to obtain a polymer melt.

[0042] In the present invention, the temperature of the mixed melting is preferably 150 to 200° C., more preferably 180 to 200° C. The present invention has no particular limitation on the time of the mixed melting, as long as the components can be formed into a uniformly distributed polymer melt. In an embodiment of the present invention, the mixed melting device can be an extruder, and the speed of the extruder can be 50 to 180 r / min.

[0043] After obtaining the polymer melt, the present invention mixes the polymer melt and a foaming agent and then granulates the mixture to obtain polymer particles.

[0044] The present invention has no particular limitation on the method for mixing the polymer melt and the foaming agent, and a conventional mixing method can be used to uniformly mix the two. In an embodiment of the present invention, the mixing method may be: injecting the foaming agent into the polymer melt, uniformly mixing the foaming agent and the polymer melt under the action of a twin screw, and then further uniformly mixing the components with the aid of a static mixer.

[0045] The present invention has no special limitation on the granulation operation method and the particle size of the granulation, and any conventional granulation method can be used.

[0046] After obtaining the polymer particles, the present invention pre-foams the polymer particles to obtain expandable gasification mold materials for lost foam casting.

[0047] In the present invention, the pre-foaming device is preferably an intermittent pre-foaming machine. In the present invention, the steam pressure of the intermittent pre-foaming machine is preferably 0.15-0.2 MPa, and the temperature of the intermittent pre-foaming machine is preferably 100-110° C. The pre-foaming under the above conditions can make the material in a good boiling state and has a better pre-foaming effect.

[0048] In the present invention, the pre-foaming atmosphere is preferably water vapor with an oxygen volume content of not less than 21%. In the present invention, the oxygen volume content is preferably not less than 22%. The present invention adopts the above atmosphere with a rich oxygen content, which can make the foam structure cavity gas of the expandable gasification mold material contain rich oxygen. Oxygen can promote the combustion and gasification of carbon atoms in the expandable gasification mold material and reduce the residual carbon products produced by foam pyrolysis; more active oxygen atoms can promote the degree and speed of cracking of the expandable gasification mold material.

[0049] The method provided by the invention is simple to operate, and conventional mixing and foaming devices can be used, with low wastewater output. In addition, the prepared expandable gasification mold material contains abundant oxygen, which can further reduce the carbon content of the expandable gasification mold material when used for lost foam casting.

[0050] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] Example 1

[0052] An expandable gasification mold material for lost foam casting is obtained by mixing and granulating the following raw materials, measured by weight: 10 parts of polystyrene GPPS1050, 40 parts of polymethyl methacrylate, 30 parts of polyether acrylate, 2 parts of SBS (melt index is 15g / 10min), 2 parts of crosslinking agent DYBP and 5 parts of foaming agent liquid nitrogen;

[0053] The preparation method of the polyether acrylate is as follows: polyether polyol PPG-1000 and (meth) acrylate are mixed in a mass ratio of 3:2, and an ester exchange reaction is performed at 120° C. for 4 hours to obtain polyether acrylate;

[0054] The preparation method of the expandable gasification mold material for lost foam casting is:

[0055] (1) mixing and melting polystyrene, polymethyl methacrylate, polyether acrylate, SBS and a crosslinking agent in an extruder at 180° C. and a rotation speed of 150 r / min to obtain a polymer melt;

[0056] (2) injecting a blowing agent into the polymer melt obtained in step (1), mixing the blowing agent and the polymer melt uniformly under the action of a twin screw, and then further mixing the components uniformly with the aid of a static mixer, and then granulating to obtain polymer particles;

[0057] (3) Pre-foaming is performed using an intermittent pre-expanding machine. The pre-foaming cylinder is first preheated to 85° C. The polymer particles obtained in step (2) are added to the pre-foaming cylinder. Then, oxygen-enriched water vapor with an oxygen volume content of 22% is introduced into the pre-foaming cylinder for pre-foaming. The oxygen-enriched steam pressure is 0.15 MPa and the temperature is 100° C. During the pre-expanding process, the material is in a good boiling state and the material level continues to rise until it reaches the discharge material level. Then, the steam heating is stopped to obtain an expandable gasification mold material for lost foam casting.

[0058] Example 2

[0059] An expandable gasification mold material for lost foam casting is obtained by mixing and granulating the following raw materials, measured by weight: 20 parts of polystyrene GPPS1050, 40 parts of polymethyl methacrylate, 25 parts of polyether acrylate, 2 parts of SBS (melt index is 15g / 10min), 2 parts of crosslinking agent DTBP and 6 parts of foaming agent liquid nitrogen;

[0060] The preparation method of the expandable gasification mold material for lost foam casting is:

[0061] (1) mixing and melting polystyrene, polymethyl methacrylate, polyether acrylate, SBS and a crosslinking agent in an extruder at 180° C. and a rotation speed of 150 r / min to obtain a polymer melt;

[0062] (2) injecting a blowing agent into the polymer melt obtained in step (1), mixing the blowing agent and the polymer melt uniformly under the action of a twin screw, and then further mixing the components uniformly with the aid of a static mixer, and then granulating to obtain polymer particles;

[0063] (3) Pre-foaming is performed using an intermittent pre-expanding machine. The pre-foaming cylinder is first preheated to 85° C. The polymer particles obtained in step (2) are added to the pre-foaming cylinder. Then, oxygen-enriched water vapor with an oxygen volume content of 22% is introduced into the pre-foaming cylinder for pre-foaming. The oxygen-enriched steam pressure is 0.15 MPa and the temperature is 100° C. During the pre-expanding process, the material is in a good boiling state and the material level continues to rise until it reaches the discharge material level. Then, the steam heating is stopped to obtain an expandable gasification mold material for lost foam casting.

[0064] Example 3

[0065] An expandable gasification mold material for lost foam casting is obtained by mixing and granulating the following raw materials, measured by weight: 40 parts of polystyrene GPPS1050, 30 parts of polymethyl methacrylate, 20 parts of polyether acrylate, 2 parts of SBS (melting index is 15g / 10min), 2 parts of cross-linking agent DTBP and 8 parts of foaming agent liquid nitrogen;

[0066] The preparation method of the expandable gasification mold material for lost foam casting is:

[0067] (1) mixing and melting polystyrene, polymethyl methacrylate, polyether acrylate, SBS and a crosslinking agent in an extruder at 180° C. and a rotation speed of 150 r / min to obtain a polymer melt;

[0068] (2) injecting a blowing agent into the polymer melt obtained in step (1), mixing the blowing agent and the polymer melt uniformly under the action of a twin screw, and then further mixing the components uniformly with the aid of a static mixer, and then granulating to obtain polymer particles;

[0069] (3) Pre-foaming is performed using an intermittent pre-expanding machine. The pre-foaming cylinder is first preheated to 85° C. The polymer particles obtained in step (2) are added to the pre-foaming cylinder. Then, oxygen-enriched water vapor with an oxygen volume content of 21% is introduced into the pre-foaming cylinder for pre-foaming. The oxygen-enriched steam pressure is 0.2 MPa and the temperature is 100° C. During the pre-expanding process, the material is in a good boiling state and the material level continues to rise until it reaches the discharge material level. Then, the steam heating is stopped to obtain an expandable gasification mold material for lost foam casting.

[0070] Comparative Example 1

[0071] An expandable gasification mold material is obtained by mixing and granulating the following raw materials, measured by weight: 10 parts of polystyrene GPPS1050, 40 parts of polymethyl methacrylate, 2 parts of SBS (melt index is 15g / 10min), 2 parts of crosslinking agent DYBP and 5 parts of foaming agent liquid nitrogen;

[0072] The preparation method of the expandable gasification mold material is:

[0073] (1) mixing and melting polystyrene, polymethyl methacrylate, SBS and a crosslinking agent in an extruder at 180° C. and a rotation speed of 150 r / min to obtain a polymer melt;

[0074] (2) injecting a blowing agent into the polymer melt obtained in step (1), mixing the blowing agent and the polymer melt uniformly under the action of a twin screw, and then further mixing the components uniformly with the aid of a static mixer, and then granulating to obtain polymer particles;

[0075] (3) Pre-foaming is performed using an intermittent pre-expander. The pre-foaming cylinder is first preheated to 85° C. The polymer particles obtained in step (2) are added to the pre-foaming cylinder. Then, oxygen-enriched water vapor with an oxygen volume content of 22% is introduced into the pre-foaming cylinder for pre-foaming. The oxygen-enriched steam pressure is 0.15 MPa and the temperature is 100° C. During the pre-expanding process, the material is in a good boiling state and the material level continues to rise until it reaches the discharge level. Then, the steam heating is stopped to obtain an expandable gasification mold material.

[0076] Comparative Example 2

[0077] An expandable gasification mold material is obtained by mixing and granulating the following raw materials, measured by weight: 10 parts of polystyrene GPPS1050, 40 parts of polymethyl methacrylate, 30 parts of polyether acrylate, 2 parts of crosslinking agent DYBP and 5 parts of foaming agent liquid nitrogen;

[0078] The preparation method of the expandable gasification mold material is:

[0079] (1) mixing and melting polystyrene, polymethyl methacrylate, polyether acrylate and a crosslinking agent in an extruder at 180° C. and a rotation speed of 150 r / min to obtain a polymer melt;

[0080] (2) injecting a blowing agent into the polymer melt obtained in step (1), mixing the blowing agent and the polymer melt uniformly under the action of a twin screw, and then further mixing the components uniformly with the aid of a static mixer, and then granulating to obtain polymer particles;

[0081] (3) Pre-foaming is performed using an intermittent pre-expander. The pre-foaming cylinder is first preheated to 85° C. The polymer particles obtained in step (2) are added to the pre-foaming cylinder. Then, oxygen-enriched water vapor with an oxygen volume content of 21 to 22% is introduced into the pre-foaming cylinder for pre-foaming. The oxygen-enriched steam pressure is 0.15 to 0.2 MPa and the temperature is 100° C. During the pre-expanding process, the material is in a good boiling state and the material level continues to rise until it reaches the discharge material level. Then, the steam heating is stopped to obtain an expandable gasification mold material.

[0082] Comparative Example 3

[0083] An expandable gasification mold material is obtained by mixing and granulating the following raw materials, measured by weight: 10 parts of polystyrene GPPS1050, 40 parts of polymethyl methacrylate, 30 parts of polyether acrylate, 2 parts of SBS (melt index is 15g / 10min), 2 parts of crosslinking agent DYBP and 5 parts of foaming agent liquid nitrogen;

[0084] The preparation method of the expandable gasification mold material is:

[0085] (1) mixing and melting polystyrene, polymethyl methacrylate, polyether acrylate, SBS and a crosslinking agent in an extruder at 180° C. and a rotation speed of 150 r / min to obtain a polymer melt;

[0086] (2) injecting a blowing agent into the polymer melt obtained in step (1), mixing the blowing agent and the polymer melt uniformly under the action of a twin screw, and then further mixing the components uniformly with the aid of a static mixer, and then granulating to obtain polymer particles;

[0087] (3) Pre-foaming is performed using an intermittent pre-expander. The pre-foaming cylinder is first preheated to 85° C. The polymer particles obtained in step (2) are added to the pre-foaming cylinder. Then, water vapor with an oxygen volume content of 2% is introduced into the pre-foaming cylinder for pre-foaming. The steam pressure is 0.15 to 0.2 MPa and the temperature is 100° C. During the pre-expanding process, the material is in a good boiling state and the material level continues to rise until it reaches the discharge level. Then, the steam heating is stopped to obtain an expandable gasification mold material.

[0088] Test Case

[0089] (1) Determination of ash content: The expandable gasification mold materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were burned in crucibles respectively. The crucibles after burning were cooled to room temperature and weighed with a precise balance. The crucibles were then wiped clean with dry toilet paper and weighed again. The difference between the two masses was the mass of the material remaining after burning. The results are shown in Table 1.

[0090] Table 1 Residues after burning of expandable gasification mold materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3

[0091] Sample mass (g) Mass of ignition residue (g) Burning residue rate (%) Example 1 1.0025 0.0071 0.71 Example 2 1.0032 0.0065 0.65 Example 3 1.0022 0.0040 0.40 Comparative Example 1 1.0026 0.0156 1.56 Comparative Example 2 1.0025 0.0085 0.85 Comparative Example 3 1.0030 0.0092 0.92

[0092] As can be seen from Table 1, the expandable gasification mold material prepared in the embodiment of the present invention has less residual amount after burning, and this property enables it to reduce the amount of residual carbon when used in lost foam casting. However, the expandable gasification mold material obtained in Comparative Example 1 has a larger residual amount after burning, which is because Comparative Example 1 does not add polyether acrylate, and the presence of polyether acrylate can reduce the residual amount after burning.

[0093] (2) The test results of various indicators of the expandable gasification mold materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 2.

[0094] Table 2 Test results of expandable gasification mold materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3

[0095]

[0096]

[0097] As can be seen from Table 2, the expandable gasification mold material provided by the present invention has the effects of high compression strength and low gas production. This makes the expandable gasification mold material provided have the potential for lost foam casting, solving the problems of high carbon content, low compression strength, and high cracking gas production in conventional lost foam casting expandable gasification mold materials.

[0098] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An expandable gasification mold material for lost foam casting, which is obtained by mixing and granulating the following raw materials, by weight: 10 to 40 parts of polystyrene, 30 to 60 parts of polymethyl methacrylate, 20 to 30 parts of polyether acrylate, 1 to 5 parts of SBS, 1 to 3 parts of a crosslinking agent and 5 to 20 parts of a foaming agent.

2. The expandable gasification mold material for lost foam casting according to claim 1, characterized in that: The preparation method of the polyether acrylate comprises: mixing polyether polyol and (meth) acrylate, and performing an ester exchange reaction to obtain the polyether acrylate.

3. The expandable gasification mold material for lost foam casting according to claim 2, characterized in that: The temperature of the transesterification reaction is 100-120°C.

4. The expandable gasification mold material for lost foam casting according to claim 3, characterized in that: The time of the transesterification reaction is 3 to 6 hours.

5. The expandable gasification mold material for lost foam casting according to claim 1, characterized in that: The crosslinking agent includes a peroxide crosslinking agent and / or an ultraviolet light crosslinking agent.

6. The expandable gasification mold material for lost foam casting according to claim 5, characterized in that: The peroxide cross-linking agent is tert-butyl peroxide.

7. The expandable gasification mold material for lost foam casting according to claim 5, characterized in that: The ultraviolet light crosslinking agent includes one or more of triallyl isocyanurate, trimethylolpropane trimethacrylate and triallyl cyanurate.

8. The expandable gasification mold material for lost foam casting according to claim 1, characterized in that: The blowing agent includes CO2 or liquid nitrogen.

9. The method for preparing the expandable gasification mold material for lost foam casting according to any one of claims 1 to 8, comprising the following steps: (1) mixing and melting polystyrene, polymethyl methacrylate, polyether acrylate, SBS and a crosslinking agent to obtain a polymer melt; (2) mixing the polymer melt obtained in step (1) with a foaming agent and granulating the mixture to obtain polymer particles; (3) Pre-foaming the polymer particles obtained in step (2) to obtain an expandable gasifiable mold material for lost foam casting; the pre-foaming atmosphere is water vapor with an oxygen volume content of not less than 21%.

10. The preparation method according to claim 9, characterized in that: The temperature of the mixed melting in step (1) is 150-200°C.

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